Inhalers or puffers are used for delivering medication into the body via the lungs. They can be used, for example, in the treatment of asthma and chronic obstructive pulmonary disease (COPD). Types of inhalers include metered dose inhalers (MDIs), Soft Mist Inhalers (SMIs), nebulisers and dry powder inhalers (DPIs).
A tidal inhaler is a class of inhaler in which the medication is consumed in multiple successive inhalations (referred to as tidal breaths) rather than a single inhalation. The patient uses their normal at rest breathing pattern without an exaggerated inhalation flow rate, also known as forced inhalation maneuver.
A spirometer is an apparatus for measuring the volume of air inspired and expired by a patient's lungs. Spirometers measure ventilation, the movement of air into and out of the lungs. From the traces, known as spirograms, output by spirometers, it is possible to identify abnormal (obstructive or restrictive) ventilation patterns. Existing spirometers use a variety of different measurement methods including pressure transducers, ultrasonic and water gauge.
Peak flow meters are used to measure peak expiratory flow (PEF), also called peak expiratory flow rate (PEFR). This is a person's maximum speed of expiration. PEF correlates with the airflow through the bronchi and thus the degree of obstruction in the airways. Peak flow readings are lower when the airways are constricted, for example due to an exacerbation of a lung condition. From changes in recorded values, patients and doctors may determine lung functionality, severity of symptoms, and treatment. Peak flow meters can also be used for diagnosis.
Spirometers and peak flow meters are generally used to monitor the lung function and/or lung health of individuals, in particular lung patients suffering from conditions such as asthma and COPD. Lung function is defined according to expiratory measures, such as PEF.
Another measure of lung function is forced expiratory volume in 1 second (FEV1). FEV1 is the volume of air that can forcibly be blown out in one second, after full inspiration. In obstructive diseases (e.g. asthma, COPD, chronic bronchitis, emphysema) FEV1 is diminished because of increased airway resistance to expiratory flow.
Patient lung function is generally monitored during appointments with medical practitioners, periodically or in response to a recurrence or worsening of symptoms. For reasons of practicality, monitoring is typically quite infrequent during periods of apparent good health. Reactive treatment is therefore not always administered as soon as it ideally would be, and preventative treatment can be used more than necessary.
Some patients find spirometers and peak flow meters tricky to use and may need training and supervision in their use. Due to this, and for reasons of cost, most patients do not possess personal spirometers or peak flow meters.
What is needed is an improved means of monitoring lung function and/or health for patients with obstructive lung conditions.